This invention relates generally to tacky floor mats of the type wherein loose dirt, dust and soil is removed from shoes, wheels and the like which contact the surface of the mat. More particularly, this invention concerns an improved provision to facilitate peeling of adhesive sheets in a stack of the same which comprises the tacky mat.
Tacky floor mats are used in hospitals, industrial clean areas, and other similar applications as a means of removing loose particles of dirt, dust, and soil of the like especially from the soles of shoes and wheels of rolling equipment. Such a tacky mat lies on the floor generally at, before or just inside the entrance of the area which is intended to be protected from loose particles which may cause contamination. Before entering such a clean area, such as an operating room in a hospital, the person must cross the tacky mat whereupon the soles of his shoes contacting the adhesive surface of the mat will cause loose particles of dirt and dust to be removed from the shoes; similarly wheels of rolling equipment which may pick up loose dirt and dust also cross the tacky mat with the wheels being stripped of the undesirable loose particles as they pass over the adhesive mat. Most tacky mats of this type include a stack of adhesive sheets which are peelable from each other in descending order. As the adhesive ability of each sheet becomes diminished upon repeated use, the top most sheet is merely peeled off, thereby exposing a fresh adhesive sheet. This stacking arrangement of adhesive sheets is not only practical, but convenient, inexpensive and efficient. One aspect of this type of mat, however, has tended to diminish the effect of these desirable features, and that involves the provision to peel each sheet from the stack after it is used and worn.
In U.S. Pat. Nos. 3,083,393 and 3,665,543, for example, tab provisions are included on or between adjacent sheets generally at one or more corners to initiate and facilitate peeling. This tab is a non-tacky insert which, while assisting in the peeling of the sheet, admittedly adds thickness to the corner of the stack where it is located on each sheet. This cumulative effect of added thickness, especially with larger numbers of sheets in the stack, increases the problem of inadvertent tripping or stumbling on the mat, causes an excessive bump when rolling equipment passes across or causes the tab areas of one or more sheets to fold over onto the top sheet producing an unsightly appearance.
Another approach to make peeling the sheet from a stack easier is discussed in U.S. Pat. No. 3,501,797. In that patent a strand or string is interleaved between two adjacent adhered sheets in the stack and protrudes from one edge thereof. To peel each sheet, the strand is merely gripped and lifted thereby separating the upper sheet from the lower sheet. Use of strands between adjacent sheets also increases the thickness of the stack in cumulative fashion especially in stacks with large numbers of sheets. Additionally, inserting a strand between two sheets requires an additional fabrication operation thereby causing production inefficiencies.
Instead of non-tacky material or tabs or strands between adjacent adhered sheets, the edges of each sheet can be left free of adhesive and beveled in the stack to facilitate peeling. Such a configuration is revealed in U.S. Pat. No. 3,785,102. In leaving the edge of each sheet, for example in a corner thereof, free of adhesive, alignment and deposition of the adhesive layer on each sheet must be carefully programmed, often with sophisticated expensive techniques and equipment. Furthermore, beveling the edges of the stack of sheets is an undesirable additional fabrication operation which further detracts from the practicability and efficiency of the tacky floor mat concept.